<!DOCTYPE html>
<html>
  <head>
    <script type="text/javascript">
      window.ERRORS = [];

      window.onerror = function(e) {
        window.ERRORS.push(e);
      };
    </script>
  </head>
  <body>
    <input type="button" value="Throw!" onclick="throw Error('boom!');"/>
  </body>
</html>
